[Bug]: Torch is not working on RX 6800

[MikuVocaloid1337]

Checklist

• [ ] The issue exists after disabling all extensions
• [x] The issue exists on a clean installation of webui
• [ ] The issue is caused by an extension, but I believe it is caused by a bug in the webui
• [x] The issue exists in the current version of the webui
• [ ] The issue has not been reported before recently
• [x] The issue has been reported before but has not been fixed yet

What happened?

Issue:

Traceback (most recent call last):
  File "G:\stable-diffusion-webui-directml\launch.py", line 48, in <module>
    main()
  File "G:\stable-diffusion-webui-directml\launch.py", line 39, in main
    prepare_environment()
  File "G:\stable-diffusion-webui-directml\modules\launch_utils.py", line 618, in prepare_environment
    raise RuntimeError(
RuntimeError: Torch is not able to use GPU; add --skip-torch-cuda-test to COMMANDLINE_ARGS variable to disable this check

After adding --skip-torch-cuda-test, WebUI works on the CPU. It worked before on RX 580 and RX Vega 56 (in 2023-2024), but the error appeared relatively recently. I tried reinstalling Torch, but it didn't help.

Steps to reproduce the problem

1. AMD GPU(maybe from RDNA 2)

What should have happened?

Previously, Torch could cope even without the GPU having CUDA cores.

What browsers do you use to access the UI ?

No response

Sysinfo

sysinfo-2025-09-26-03-29.json

Console logs

venv "G:\stable-diffusion-webui-directml\venv\Scripts\Python.exe"
Python 3.10.6 (tags/v3.10.6:9c7b4bd, Aug  1 2022, 21:53:49) [MSC v.1932 64 bit (AMD64)]
Version: v1.10.1-amd-43-g1ad6edf1
Commit hash: 1ad6edf170c2c4307e0d2400f760a149e621dc38
Traceback (most recent call last):
  File "G:\stable-diffusion-webui-directml\launch.py", line 48, in <module>
    main()
  File "G:\stable-diffusion-webui-directml\launch.py", line 39, in main
    prepare_environment()
  File "G:\stable-diffusion-webui-directml\modules\launch_utils.py", line 618, in prepare_environment
    raise RuntimeError(
RuntimeError: Torch is not able to use GPU; add --skip-torch-cuda-test to COMMANDLINE_ARGS variable to disable this check

Additional information

No response

[CS1o]

It seems you followed an old tutorial to install the webui. Please follow the Automatic1111 with Zluda setup guide from here: https://github.com/CS1o/Stable-Diffusion-Info/wiki/Webui-Installation-Guides Then it will work.